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| United States Patent |
6,149,819
|
|
Martin
, et al.
|
November 21, 2000
|
Air and water purification using continuous breakpoint halogenation and
peroxygenation
Abstract
A process for optimizing the rate of oxidation using a combination of
halogen, e.g. chlorine donors and peroxygen, e.g. potassium
monopersulfate. The peroxygen compound elevates the oxidation-reduction
potential of the body of water being treated. Simultaneously, a halogen
donor is added to the body of water to maintain a PPM level of free
halogen sufficient to insure sanitization. The feed rates and
concentrations of both oxidizers are optimized so as to achieve and
maintain the targeted parameters. A high level of oxidation is maintained
which removes by-products from the water and surrounding air.
| Inventors:
|
Martin; Roy (Downers Grove, IL);
Ferri; Mikel Anthony (Bradley, IL)
|
| Assignee:
|
United States Filter Corporation (Palm Desert, CA)
|
| Appl. No.:
|
260810 |
| Filed:
|
March 2, 1999 |
| Current U.S. Class: |
210/743; 210/746; 210/752; 210/754; 210/755; 210/756; 210/759; 210/764; 210/908; 210/916 |
| Intern'l Class: |
C02F 001/76 |
| Field of Search: |
210/743,746,752,754-756,758,759,764,908,916
|
References Cited
U.S. Patent Documents
| 3702298 | Nov., 1972 | Zsoldos et al. | 210/759.
|
| 4752740 | Jun., 1988 | Steininger | 210/169.
|
| 5130033 | Jul., 1992 | Thornhill | 210/754.
|
| 5306432 | Apr., 1994 | Puetz | 210/759.
|
| 5332511 | Jul., 1994 | Gay et al. | 210/755.
|
| 5683654 | Nov., 1997 | Dallmier et al. | 422/14.
|
| 5814233 | Sep., 1998 | Starkey et al. | 210/759.
|
| 5849985 | Dec., 1998 | Tieckelmann et al. | 210/759.
|
| 5858246 | Jan., 1999 | Rafter et al. | 210/754.
|
| 5882526 | Mar., 1999 | Brown et al. | 210/753.
|
Primary Examiner: Hruskoci; Peter A.
Attorney, Agent or Firm: Mchale & Slavin
Parent Case Text
This invention is related to co-pending application Ser. No. 09/206,809,
entitled "Air and Water Purification Using Continuous Breakpoint
Halogenation" the contents of which are herein incorporated by reference.
Claims
What is claimed is:
1. A process for removing volatile halogenated compounds including
chloramines and/or bromamines from the air and treating a body of water in
an indoor aquatic facility comprising:
disposing an oxidation-reduction potential (ORP) sensor in fluid
communication with a body of water within said facility;
continuously monitoring the ORP of said body of water;
comparing the monitored ORP to a set-point value calculated to be within a
range effective to permit oxidation of said volatile halogenated
compounds, wherein the effective range of ORP is from 750 mv-850 mv;
adding a halogen donor source in an amount and at a rate sufficient to
realize an optimum free halogen level sufficient to sanitize said body of
water;
adding a peroxygen compound at a rate and in an amount sufficient to
maintain the ORP within said effective range;
optimizing the ratio of halogen donor source to peroxygen compound to
sustain the optimum free halogen level while maintaining the effective ORP
value;
maintaining a sustained high rate of oxidation in said body of water
sufficient to cause the volatile halogenated compounds in the air to be
reabsorbed therein; and
oxidizing the reabsorbed compounds.
2. The process according to claim 1 wherein said halogen donor source is
selected from the group consisting of trichloroisocyanuric acid,
dichloroisocyanuric acid, sodium bromide, hydantoin based bromines,
gaseous chlorine, calcium hypochlorite, sodium hypochlorite, lithium
hypochlorite and mixtures thereof.
3. The process according to claim 1 wherein the effective range of ORP is
from 760 mv-800 mv.
4. The process according to claim 1 wherein the optimum free halogen level
is within a range of 0.2 to 10.0 ppm.
5. The process according to claim 1 wherein the peroxygen compound is
selected from the group consisting of hydrogen peroxide, sodium peroxide,
sodium perborate, potassium monopersulfate, sodium peroxydisulfate,
potassium peroxide, potassium perborate, sodium monopersulfate, potassium
peroxydisulfate, ammonium peroxydisulfate and ammonium monopersulfate.
6. The process according to claim 1 further including the step of
monitoring and controlling pH.
7. A process for removing dissolved halogenated compounds including
chloramines and/or bromamines and preventing their accumulation in
circulating water systems comprising:
disposing an oxidation-reduction potential (ORP) sensor in fluid
communication with said circulating water system;
continuously monitoring the ORP of said system;
comparing the monitored ORP to a set-point value calculated to be within a
range effective to permit oxidation of said halogenated compounds wherein
the effective range of ORP is from 750 mv-850 mv;
adding a halogen donor source in an amount and at a rate sufficient to
realize an optimum free halogen level sufficient to sanitize said body of
water;
adding a peroxygen compound at a rate and in an amount sufficient to
maintain the ORP within said effective range;
optimizing the ratio of halogen donor source to peroxygen compound to
sustain the optimum free halogen level while maintaining the effective ORP
value; and
maintaining a sustained high rate of oxidation in said body of water
sufficient to destroy any dissolved halogenated compounds within said body
of water and prevent further accumulation thereof.
8. The process according to claim 7 wherein said halogen donor source is
selected from the group consisting of gaseous chlorine, calcium
hypochlorite, sodium hypochlorite, lithium hypochlorite and mixtures
thereof.
9. The process according to claim 7 wherein the effective range of ORP is
from 760 mv-800 mv.
10. The process according to claim 7 wherein the optimum free halogen level
is within a range of 0.2 to 10.0 ppm.
11. The process according to claim 7 wherein the peroxygen compound is
selected from the group consisting of hydrogen peroxide, sodium peroxide,
sodium perborate, potassium monopersulfate, sodium peroxydisulfate,
potassium peroxide, potassium perborate, sodium monopersulfate, potassium
peroxydisulfate, ammonium peroxydisulfate and ammonium monopersulfate.
12. The process according to claim 7 further including the step of
monitoring and controlling pH.
Description
FIELD OF THE INVENTION
This invention relates to the maintenance of aquatic facilities, and in
particular, to the optimization of the feed rates of a sanitizer/oxidizer
and peroxygen compound to eliminate the accumulation of undesirable
halogenated compounds, thereby increasing water and air quality within
such facilities.
BACKGROUND OF THE INVENTION
The use of closed recirculating water reservoirs for use by the general
public, for example, swimming pools, spas, hot tubs, decorative fountains,
cooling towers and the like, has led to a variety of water quality
problems. For instance, improper chemical balances in the water can lead
to various types of contamination including bacterial and viral
contamination.
The use of chemical sanitizers is a fairly standard water sanitation
method. Addition of so-called halogen donor compounds, such as chlorine or
bromine are effective sanitizers so long as they are maintained at well
defined and constantly controlled concentration levels in the water. It is
important that the concentration of these chemical sanitizers is not
allowed to become too high which may cause irritation to the users and
damage to the water system. Insufficient sanitizers result in a
contaminated condition.
The difficulties in maintaining a proper balance of sanitizers may arise
from numerous load factors that are difficult, if not impossible, to
predict. For instance, in a pool the load factor is typically caused by
varying numbers of users. In hot tubs the use of air jets and high water
temperatures tend to destroy or remove the sanitizer from the water.
Cooling towers are subject to environmental conditions, such as
fluctuations in temperature. Indoor decorative fountains may be affected
by the air quality in the building, while the fountain water can also
affect the air in the building.
Various testing devices exist for determining the chemical balance of the
water of pools, spas and the like, for example, colormetric chemical test
kits are available that utilize liquid droplets, test strips or tablets
which dissolve in the water to indicate a particular level or
concentration of sanitizing agents. By removing a test sample of water,
for example via a scoop or cup, a seemingly representative sample is
deemed to have been taken. A staining agent is then added by means such as
an eye dropper or the like. The degree of staining relates to the amount
of sanitizer in the water. The amount of sanitizer present is determined
by visually comparing the degree of coloring of the test sample against a
test scale previously formulated. Further complicating the task of
maintaining sanitary conditions in such bodies of water is the fact that
studies now indicate there is little correlation between the free halogen,
e.g. chlorine, residual readings which are normally used to monitor such
bodies of water and the actual bacteriological quality of the reservoirs
themselves. Pool and spa maintenance officials have long gone under the
assumption that maintaining a free chlorine residual of two milligrams per
liter or two parts per million will insure a safe water condition. Thus,
the parts per million reading which is determined via the stain
comparison, is actually a reflection of the sum of the free chlorine and
combined chlorine compounds such as chloramine which are present in the
water. These combined chlorine derivatives do not protect from bacteria
and/or viral contamination. Additionally, since organic and chemical
loading drastically reduce the ability of free chlorine to overcome
bacteria, the available free chlorine test kits are of questionable value
unless the exact levels of organic contaminants and the particular pH of
the water being tested is known.
U.S. Pat. No. 4,752,740 suggests the use of monitoring the
oxidation-reduction potential (ORP) as a method of measuring the
sanitization levels of water. ORP defines the potential of a sanitizer
such as chlorine, bromine or ozone to react with various contaminants.
These compounds are known as oxidizers and have the property of "burning
off" impurities in the water, for example, body wastes, algae and
bacteria. The use of an ORP sensor allows the pool maintenance engineer to
measure the potential generated by the active form of the sanitizer and
not the inactive forms such as the combined chlorine derivatives.
Additionally, ORP monitoring has an advantage in that it is an ongoing
electronic process requiring no test chemicals or agents and monitoring of
sanitation levels is constantly performed as opposed to being performed on
some predetermined schedule basis. Since the potential for disease
transmission due to organic loading is far more significant in public spas
and pools, use of ORP measurement could be of great benefit in reducing
the risk of contamination and disease transmission.
In accordance with standards set forth by the World Health Organization in
1972, maintenance of an ORP level of 650 millivolts is deemed to result in
a water supply that is disinfected and in which viral inactivation is
virtually instantaneous.
Chlorine is the most widely used oxidizer in the aquatic industry, the
primary use being for sanitation of the water in pools and spas. Chlorine,
being an oxidizer, is also involved in oxidation reactions with various
organics, as well as inorganic and organic nitrogen based substances such
as urea, uric acid, amino acids, etc. One of the drawbacks of chlorine is
the production of chlorinated byproducts resulting from incomplete
oxidation. These byproducts are often volatile and produce undesirable
side effects such as irritation of the eyes, sinuses, skin, foul smelling
air, and corrosion of air handling equipment.
The health department generally regulate the concentration of Free (HOCL &
OCL) chlorine in the water. In some locations, sufficient HOCL is not
available to maintain a sufficient rate of oxidation of the demand being
contributed to the water. This allows for the accumulation of these
undesirable substances. Substances which oxidize following
substoichiometric oxidation react with the chlorine producing
substoichiometric and/or stoichiometric compounds. Further oxidation with
HOCL eventually leads to increased concentration of substances that follow
stoichiometric oxidation, such as monochloramines. If enough HOCL is not
maintained to meet the stoichiometric ratios needed to drive oxidation of
the chloramines, no demand on the HOCL is experienced. However, when the
chlorine donor(s) are controlled using ORP control with an optimized ORP
setting of between 780-800 mV, the buffering effect chloramines place on
the ORP becomes a significant factor. The buffering effect provided by the
chloramines reduces the impact on ORP provided by the addition of more
chlorine donor(s). The controller feeds more chlorine donor(s) to achieve
the optimized ORP. This often leads to levels of Free Chlorine which
exceed local maximum limits. In order to meet the maximum limits of free
chlorine, the ORP is reduced so as to not exceed the established limit.
This allows for the volatile chlorinated compounds to accumulate, thereby
increasing the partial pressure which promotes fouling of the air.
Numerous attempts have been made at addressing this problem. "Shocking" of
the pool water requires dosing the water with stoichiometric
concentrations of chlorine to oxidize the substances. One problem with
this method is that there cannot be any bathers present due to the
excessive concentrations of chlorine required to meet the stoichiometric
levels needed when said undesirable substances have been allowed to
accumulate. Another issue is this method is generally applied after the
symptoms have appeared, i.e. high combined chlorine, foul odors, etc. In
many cases this method fails to rid the water and air of these substances
since the concentration of chlorine required is at best a rough estimate
(incorporates measuring the combine chlorine in the water). Measuring the
concentration of combined chlorine in the water does not take into
consideration the accumulated demand that is non-aqueous, e.g. that
accumulated on the filter media, walls of the pools, etc. As the chlorine
levels rise, some of the accumulated demand is liberated. This gives the
appearance that the system had not been driving breakpoint when indeed it
probably did for awhile. The fact that the free chlorine levels drop
considerably, and the combined chlorine level still appears, is an
indication the HOCL must have oxidized the combined chlorine and/or
accumulated demand, thereby providing a source of readily available
oxidizable substances not originally detected in the water. When the free
chlorine levels rise, they oxidize substances in the filters and the
remaining system. This releases more substances into the water which were
not accounted for, the stoichiometric ratio of HOCL is overtaken, and
breakpoint is not achieved.
Ozone has been used as a side stream treatment to destroy these undesirable
substances. While effective, ozone cannot be applied to the bulk water of
the pool where the contaminants are being added. Also, since ozone cannot
be used as a stand-alone treatment since it cannot maintain a residual in
the water, chlorine or bromine is used as the primary sanitizer. Besides
being expensive and often requiring extensive deozonation equipment, e.g.
such as activated carbon, ozone destroys chlorine by attacking the
hypochlorite ions, thereby further increasing operational and maintenance
cost.
Bromine is sometimes used in place of chlorine because of the belief it
does not produce the air fouling byproducts produced by chlorine. However,
while bromamines are not as volatile as chloramines, they do possess an
odor and irritate the eyes. Bromine also requires an oxidizer such as
chlorine or ozone to activate the bromide ion. Operating costs tend to be
high and it is often difficult to maintain water quality since no easy
methods are available for differentiating between free or combined
bromine. Also, hydantoin, an additive commonly used to pelletize the
bromine chlorine combination, reduces the oxidizing power of the bromine
as the hydantoin accumulates in the water. This makes it more difficult to
reduce the accumulation of undesirable brominated compounds.
Non-chlorine shock treatments incorporating peroxygen compounds, e.g.
potassium monopersulfate (MPS) have been sold under the brand name
OXY-BRITE for addressing the chloramine issue. Despite the application of
this product following manufacturer's guidelines, many pools continue to
experience chronic air and water quality problems. The method of shock
feeding is a means of addressing the symptoms resulting after the problem
makes them apparent, e.g. high chlorine concentration and foul odors. MPS
is approved for use as a shock treatment while bathers are present.
However, when applied to systems using chlorine donor(s) which are fed
using ORP control, the system experiences undesirable side effects from
shock feeding MPS. The addition of MPS increases the ORP of the chlorine
donor(s) system. When MPS is added, the ORP of the system rises above that
provided by the chlorine donor(s) As long as the ORP value remains above
the set point established for the chlorine donor(s) system, no chlorine
donor is fed. Since many of the contaminants entering the water do not
react directly with MPS without first being oxidized by the chlorine
donor(s), these substances further accumulate, thereby compounding the
problem.
SUMMARY OF THE INVENTION
This invention incorporates an innovative process that allows the aquatic
facility to maintain the desired ORP and oxidize the chlorinated volatile
substances in the bulk water, while not exceeding the free chlorine limits
established by local health departments.
This process incorporates optimization of the rate of oxidation by
controlling the feedrate and ratio of two oxidizers, the primary oxidizer
being a halogen donor, e.g. trichloroisocyanuric acid, dichloroisocyanuric
acid, sodium bromide, hydantoin based bromines, gaseous chlorine, calcium
hypochlorite, sodium hypochlorite, lithium hypochlorite and mixtures
thereof; the other being a peroxygen compound selected from hydrogen
peroxide, sodium peroxide, sodium perborate, potassium monopersulfate,
sodium peroxydisulfate, potassium peroxide, potassium perborate, sodium
monopersulfate, potassium peroxydisulfate, ammonium peroxydisulfate,
ammonium monopersulfate and mixtures thereof. In a preferred embodiment
the peroxygen compound is potassium monopersulfate (MPS). The ratio of MPS
to halogen donor, e.g. chlorine donor(s) is optimized to sustain the
desired PPM range of chlorine, while achieving an ORP of 780-820 mV. By
optimizing and controlling the feedrate and ratios of a halogen donor to
maintain the desired ORP, the rate of oxidation is maintained at a level
sufficient to prevent the accumulation of undesirable halogenated
byproducts. When applied to an aquatic facility, the effects of poor air
and water quality can be reduced and even eliminated.
The process optimizes the ORP by incorporating the necessary process
control and feed equipment to sustain a set-point thereby controlling the
concentration of undesirable by-products in the water.
An objective of the invention is to eliminate volatile halogenated
compounds from water and air by maintaining a level of oxidation
potential. The feedrate and ratio of halogen donor and peroxygen compound
are optimized to sustain the desired PPM range of halogen and sustain an
ORP of 780-820 mv. Sustaining these parameters will prevent or even
reverse the accumulation of combined halogen and other halogenated
volatile compounds which contaminate the air and water of aquatic
facilities, in particular indoor aquatic facilities.
Another objective of the invention is to teach a process of operating an
aquatic facility under conditions of "Continuous Breakpoint Halogenation
and Peroxygenation".
Yet another objective of the invention is to improve the air quality around
closed water systems by removal of halogenated compounds through
re-absorption followed by oxidation thereof with, e.g. HOCL.
Other objectives and advantages of this invention will become apparent from
the following description taken in conjunction with the accompanying
drawings wherein are set forth, by way of illustration and example,
certain embodiments of this invention. The drawings constitute a part of
this specification and include exemplary embodiments of the present
invention and illustrate various objects and features thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic representation of the process of the instant
invention.
FIG. 2 is a Circuit Diagram of the Air and Water Flow in the test device
according to Example 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
It is to be understood that while a certain form of the invention is
illustrated, it is not to be limited to the specific form or arrangement
of parts herein described and shown. It will be apparent to those skilled
in the art that various changes may be made without departing from the
scope of the invention and the invention is not to be considered limited
to what is shown in the drawings and described in the specification.
Referring to FIG. 1, a typical indoor aquatic facility is characterized.
Water from the pool or spa flows past an ORP sensor. Optionally, the water
may further flow past a sensor which measures total dissolved solids
(TDS), temperature and pH. Output from the ORP sensor is transmitted to a
controller which calls for the addition of both a halogen donor source and
a peroxygen source to the pool water in accordance with selected process
parameters.
An innovative process has been developed that allows the aquatic facility
to maintain the desired ORP, oxidize the halogenated volatile substances
in the bulk water, while not exceeding the free halogen limits established
by local health departments.
Oxidation Reduction Potential is a qualitative measurement of the oxidation
or reduction power of a solution. ORP controllers have been used in
aquatics since 1972 when the Stranco Company developed and introduced
these systems to the industry. Despite the use of ORP controllers in tens
of thousands of aquatic facilities, the issue of poor air and water
quality continues to be the universal and primary problem with indoor
aquatic facilities.
While ORP has been established as the primary indicator of determining the
inactivation rates of various bacteria and viruses, dosing aquatic water
with part per million (PPM) measurement of halogen has been the method
used for meeting the oxidation needs of the aquatic facility. For example,
while 650 mV is commonly used as the minimum required oxidation potential
to ensure sanitized conditions in a pool or spa, the health departments
still require PPM levels of halogen, e.g. chlorine.
Despite maintaining health departments levels of halogen and/or operating
with ORP levels in excess of 650 mV, following prescribed methods of
superchlorination (breakpoint chlorination) as described on the product
literature and in the "Certified Pool Operators" (CPO) training course,
the problems resulting from incomplete oxidation are widespread.
This process incorporates optimizing the rate of oxidation by controlling
the feedrate and ratio of two oxidizers, the primary oxidizer being a
halogen donor(s), the other being a peroxygen compound, e.g. Potassium
monopersulfate (MPS). The ratio of MPS to halogen donor(s) is optimized to
sustain the desired PPM range of halogen, while achieving an ORP of
780-820 mV. By optimizing and controlling the feedrate and ratios of a
halogen donor to maintain the desired ORP, the rate of oxidation is
sufficient to prevent the accumulation of undesirable chlorinated
byproducts. When applied to an aquatic facility, the effects of poor air
and water quality can be reduced and even eliminated.
It has been demonstrated that optimizing the ratio of halogen donor(s) to
peroxygen compound, while controlling their combined feedrate using ORP,
effectively reduces or eliminates the problems resulting from the
accumulation of volatile halogenated substances. This is achieved while
maintaining lower PPM levels of free halogen than is otherwise required in
a strictly halogen donor(s) system.
This process involves: achieving and sustaining an optimum concentration of
free halogen, e.g. free chlorine, of between 0.2-10 ppm, addition of
peroxygen, e.g. MPS to raise the solution's ORP to 750-850 mV (preferably
760-800 mV), controlling the feed of both oxidizers using an ORP
controller, optimizing the ratio of halogen donor(s) to peroxygen compound
to sustain the optimized halogen donor(s) while achieving the desired ORP.
By sustaining these conditions, the problems created by poor air and/or
water quality resulting from the presence of these undesirable byproducts
can be reversed.
This invention ensures a sustained high rate of oxidation in the bulk water
of the pool, spas, and other aquatic water systems despite the presence of
accumulated demand. It has been found that the undesirable byproducts
cannot be sustained in an environment possessing this level of oxidation
potential. Therefore, by implementing this invention, the aquatic facility
will be operating under the conditions of "Continuous Breakpoint
Chlorination".
By operating in the conditions described, the byproducts produced during
the initial step of oxidation are not allowed to accumulate. The
byproducts are an intermediate step in the continuing process of
oxidation. While these byproducts are initially produced, they are not
allowed to accumulate, and shortly thereafter, are destroyed by the
continued oxidation. By preventing the accumulation of these volatile
byproducts, their respective partial pressures are minimized, and the
problems of poor air quality are minimized or prevented. Also, in aquatic
facilities that currently experience these problems, by implementing this
application, the problems of poor air quality resulting from these
chlorinated compounds can be reversed through re-absorption of the
volatile chlorinated compounds, followed by oxidation, even while
maintaining substoichiometric levels of free halogen. The re-absorption
process follows Henry's Law of Diffusion.
This development is important to the aquatics industry since its
implementation means halogen feedrates can be controlled below maximum
regulated levels while preventing or even reversing the accumulation of
combined halogen and other chlorinated volatile compounds which
contaminate the air and water of aquatic facilities, in particular, indoor
aquatic facilities.
EXAMPLE 1
A testing device as shown in FIG. 2 was designed and built to simulate the
water and air environment of an indoor aquatic facility. The system was
designed to control the following:
H.sub.2 O temperature;
Air circulation rates;
Air exchange rates;
Water turnover rates (filtered water);
Water exchange rates.
Instrumentation for automatic monitoring and recording of ORP and pH were
incorporated.
A condenser was installed in the air circulation system. The condenser
allowed for scheduled sampling of the condensate.
A micro-titration system was incorporated for precise feed of various
reagents for adjusting ORP, pH, etc.
The test device was initially prepared for use by the addition of water to
50% of the skimmer line. The tank representing the surge pit was filled to
50%. The tank lid was sealed.
Condensate samples were collected by chilling the air prior to the air
circulation pump. Condensate was collected for 20 minutes, the measured
sample was tested using standard DPD methods for chlorine that
incorporated a HACH DR2000 spectrophotometer.
Laboratory grade ammonium chloride was used as the nitrogen source for the
generation of chloramines. A measured amount was added to the water of the
test device. The water and air circulation pumps were activated and
adjusted to achieve desired circulation and exchange rates.
A measured dosage of chlorine in the form of 5.25% liquid bleach was added
to the water to induce the formation of combined chlorine. After providing
sufficient contact time, incremental dosages of bleach were added to
achieve and sustain the desired ORP of 800 mV. Condensate and water
samples were periodically tested for free and total chlorine using
standard methods. ORP and pH readings were also recorded.
TABLE 1
______________________________________
Lapsed Time
ppm free ppm combined
ppm combined
(minutes) (water) (water) (condensate)
______________________________________
0 0.24 1.50 0.00
45 4.50 4.35
90 4.46 2.18
135 4.40 1.75
180 4.32 1.45
225 4.26 1.40
______________________________________
Results demonstrate that a comparable rate of chloramine destruction can be
achieved while sustaining lower concentrations of free available chlorine,
at an oxidation potential of approximately 780 mV.
EXAMPLE 2--FIELD TRIAL
An indoor aquatic facility with a 166,500 gallon lap-pool, and a 14,400
gallon splash pool incorporating a water slide had experienced chronic air
and water quality problems. Combined chlorine in the water of both pools
(water is mixed in the surge tank), was consistently above 1.00 ppm. Odors
in the air were strong from chloramines.
The facility had utilized an ORP control system with calcium hypochlorite
as the primary sanitizer/oxidizer. Potassium monopersulfate had been fed
at 4 times the suggested concentrations as described on the manufacturer's
directions. Superchlorination had been incorporated every 3 weeks at a
concentration three times that taught by the Certified Operators Training
(CPO), and the Aquatic Facilities Operator (AFO) course.
Initially, condensate from the air handling systems dehumidifier was
collected and tested using standard methods FAS-DPD test for chlorine.
Day One--3:00 pm . . . 0.6 ppm total chlorine
Day One--7:00 pm . . . 0.8 ppm total chlorine
Day Two--9:00 am . . . 0.8 ppm total chlorine
Initially, the system was started using calcium hypochlorite to achieve the
targeted ORP of 780 mV. The Free Chlorine levels needed to sustain the ORP
at 780 mV generally ranged from 4 to 6 ppm, with one day requiring 18 ppm
during a high chlorine demand period.
The two oxidizer approach in accordance with the teachings of the instant
invention was then instituted using calcium hypochlorite and potassium
monopersulfate. The oxidizers' feed rate was optimized to achieve the
desired free chlorine concentration in the water (1.5-2.0 ppm), while
sustaining the targeted ORP of 780 mV using monopersulfate.
Within 3 days of implementing the new program, the combined chlorine in the
water dropped to undetectable levels using FAS-DPD test for chlorine &
Total Oxidant. Free chlorine was consistently between the 1.0-2.0 ppm, and
ORP was held at 780 mV.+-.1.0%. The odors and skin and eye irritation
problems were eliminated.
To help quantify the reduction in chloramines from the air, condensate
samples were later tested following standard DPD methods.
Day One--6:30 am . . . 0.0 ppm (no color change after 2 minutes)
Day One--7:30 pm . . . 0.0 ppm (no color change after 2 minutes)
Day Two--9:00 am . . . 0.0 ppm (no color change after 2 minutes)
Along with the dramatic improvements in air and water quality, chemical use
dropped:
______________________________________
Chemical used Before (lbs/week)
After (lbs/week)
______________________________________
Monopersulfate 74 55
Calcium hypochlorite
80 25
Chlorine shock 69 0
______________________________________
Although the invention is described in terms of a specific embodiment, it
will be readily apparent to those skilled in this art that various
modifications, rearrangements and substitutions can be made without
departing from the spirit of the invention. The scope of the invention is
defined by the claims appended hereto.
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